Hi all,
might be a total beginner question :o
Is it possible to connect different types of I/O to arduino, without a shield?
for example - let's say I want to connect this oled display module -
or even a more complex I/O - btle module like this one -
The question is basically if it's technically possible to connect a non-shield modules to arduino? does it event makes sense to do so?
Thanks.
You need to be really careful with stuff like this because often such devices operate on lower voltages than the typical 5 V Arduinos.
Unless there are level shifters to match the voltages, you risk damaging your modules.
Shields and breakout boards often incorporate such shifters, but bare device almost certainly won't
Thanks @AWOL. Sure I'll be carefult 
- The question is - how is it possible? how do I wire it into the Arduino and also - how to I "talk" with it?
The documentation that comes with the device, typically linked from the vendor's sales listing, should tell you how to connect and use the device. If you have bought from a vendor that provides no support you would typically look for a library that supports the device. The library documentation should cover how to hook things up and the library will typically come with some example sketches that let you exercise the device and that will act as a basis for your sketch.
To connect random breakout boards (what non-shield boards are typically called) you can use breadboards for temporary connections. You should get a bunch of jumper wires with two male ends, two female ends, and one of each. The male ends fit into the sockets on the Arduino and into the sockets on the breadboard. The female ends fit on pin headers often soldered into breakout boards.
Get some rows of pin headers. They come in rows of 40 and can be broken to any shorter length. You can plug them into female headers (like the Arduino has) to give you some place to solder wires.